/* 
 * [New BSD License (BSD 3-Clause License)]
 * Copyright (c) 2012, Max Bechtold
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *     - Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     - Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     - Neither the name of the Rel2Xml Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package maxbe.rel2xml.generator.dml.predicates;

import static maxbe.rel2xml.util.Config.getBoolean;
import maxbe.rel2xml.generator.dml.ResultColumn;
import maxbe.rel2xml.util.Config;

/**
 * Represents a simple null test for columns
 * 
 * @author Max Bechtold
 * 
 */
public class NullCheck implements Predicate {

	private final ResultColumn column;
	private final boolean negate;

	public NullCheck(ResultColumn column, boolean negate) {
		this.column = column;
		this.negate = negate;
	}

	@Override
	public String toXQuery() {
		return toXQuery(false);
	}

	@Override
	public String toXQuery(boolean omitAliases) {
		if (omitAliases) {
			if (getBoolean(Config.OMIT_NULLS))
				return String.format(
						(negate ? "fn:exists(%s)" : "fn:empty(%s)"),
						column.getXmlName());
			else
				return String.format((negate ? "%s <> \"\"" : "%s = \"\""),
						column.getXmlName());
		} else {
			if (getBoolean(Config.OMIT_NULLS))
				return String.format((negate ? "fn:exists($%s/%s)"
						: "fn:empty($%s/%s)"), column.getEntity().getAlias(),
						column.getXmlName());
			else
				return String.format((negate ? "$%s/%s <> \"\""
						: "$%s/%s = \"\""), column.getEntity().getAlias(),
						column.getXmlName());
		}
	}

	@Override
	public String toSql() {
		return column.getName() + " is " + (negate ? "not " : "") + "null";
	}

	@Override
	public String toString() {
		return toSql();
	}

}
